This leaves us with the "leader that seldom speaks", "each member of the group having a speciality", "defending the village with stakes and such" and "the slow motion battle in the rain of few on foot vs. many mounted".
The first one is a common trope: "stoic warrior". That is older than Seven Samurai and I see no reason to think the influence came from just that one movie. The second is a necessity of making any movie about a group of otherwise similar people, so that the audience can keep track of who is who. That would have been in 13th Warrior whether or not Seven Samurai was ever made, because it has to. The third is just a common sense realization of how to defend a village vs. attackers. Castles have moats, villages have palisades. That idea is far older than movies are, and there is no reason to expect that one movie only got that idea from the other.
The last one is possibly convincing, since you have a lot of separate events coming together. "Rain", "On foot vs. Mounted" and "Slow Motion". So I could imagine that *this one scene* was inspired by a scene in another movie, but that is about it. And many movies do that. A kinder word than "rip off" would be "homage". And, on the other hand, I could also believe in parallel thinking.